Answer: Option E.
glycosaminoglycans
Step-by-step explanation:
Proteoglycans are core proteins that are attached to glycosaminoglycans chains via covalent bond because
glycosaminoglycans consist of repeating disaccharide units composed of an N-acetylated or N-sulfated hexosamine and either a uronic acid or galactose . They are found in connective tissues and cell matrix of animal cells.